Methanesulfonic Acid Solution Research Articles

Enrichment of a Nigerian plagioclase-rich feldspar ore by methanesulfonic acid solution for improved industrial application: kinetic and statistical analysis

ABSTRACT To date, feldspar is a pivotal mineral, with projections indicating a substantial gap between supply and demand in the near future. This surge can be attributed to the increasing need for ceramic tiles, the growing demand for electronic devices, and advancements in glass manufacturing, which have led to the development of a specialised hydrometallurgical process capable of producing iron-free feldspar materials tailored for the ceramics and glass industries. Consequently, the enrichment of a locally sourced plagioclase-rich feldspar ore containing admixtures of albite (Na2.00Al2.00Si6.00O16.00:96-900-1633), anorthite (Ca8.00Si16.00Al16.00O64.0:96-900-0362), and quartz (Si3.00O6.00:96-901-2601) by the hydrometallurgical process was examined in methanesulfonic acid media. The experimental parameters during leaching including leachant concentration, pH, reaction temperature, and particle size on the ore dissolution were investigated and correlated with SPSS statistics version 25 using a mixed-effect model. At established conditions (4.0 mol/L MSA, 75 °C, pH = 2, – 75 + 56 µm), 94.50% iron removal efficiency within 120 minutes. The estimated activation energy of 18.65 kJmol−1 supported the proposed mixed control reaction mechanism as the rate-determining step for the ore enrichment.

Selective leaching of lead from complex polymetallic sulfide secondary concentrate with ferric methanesulfonate and methanesulfonic acid solution

The selective leaching of lead from complex polymetallic sulfide secondary concentrate (CPSSC) with the solution mixed by ferric methanesulfonate and methanesulfonic acid (Fe(MS)3-MSA) was investigated by leaching experiments, analysis of solids, and electrochemical characterizations. The leaching results showed that stirring rate, liquid–solid ratio, temperature, and ferric concentration greatly influenced Pb extraction rate. At the optimum leaching conditions, 93.1 % Pb, while 3.8 % Cu and 18.8 % Fe were extracted. The selective leaching mechanism was related to the activity of PbS in Fe(MS)3-MSA solution and the galvanic effect between sulfides. XRD and SEM-EDS results of leaching residues verified the selective decreases in PbS, and retainment of most Cu, Fe, and Zn. Electrochemical characterizations demonstrated a more stable and higher open-circuit potential, and an increase/decrease in A0 peak potential/current in LSV curve for the residue’s electrode, suggesting the selective decreases in active components (e.g. PbS). After selective leaching, Cu could be easily extracted from residues by pressurized water leaching, and Fe(MS)3-MSA solution could be regenerated for recycling used in leaching. These results indicate the great potential of Fe(MS)3-MSA solution to selectively leach and separate Pb from CPSSC, and unveil a method to effectively treat refractory CPSSC.

Clean and efficient preparation of metallic bismuth from methane-sulfonate electrolyte in the membrane electrolysis cell

As a prevailing hydrometallurgical extraction system for bismuth sulfide concentrate, the acidic chloride solution has superior applicability to raw materials and high recovery ratio of metallic bismuth. Nevertheless, it has disadvantages of being easily volatile and strongly corrosive, as well as large energy consumption and poor deposition morphology during chloride electrolysis. Methane-sulfonic acid (MSA) solution is widely considered as the next generation of green hydrometallurgical system, due to its excellent physicochemical properties such as high metal salts solubility, low volatility, and biodegradability. In this study, membrane electrolysis technique was adopted based on the acidic bismuth methane-sulfonate leaching solution, and the influence of electrolyte composition, cathode current density (CCD), and temperature parameters on the bismuth conversion ratio (BCR) and deposition rate (BDR), techno-economic indicators and cathodic bismuth morphology were studied. The results show that the CCD affects the deposits morphology significantly, and the bismuth metal is partially dark and composed of loose ellipsoidal particles at high current density. Under the optimal conditions (70 g/L Bi3+ ions, 5 g/L Fe2+ ions, 110 g/L MSA, 35 °C, 180 A/m2), high-purity metallic bismuth (Bi 99.97 %) with silver-white luster is obtained. The BCR and BDR are 9.43 % and 0.46 kg/(h·m2), respectively. The cathodic current efficiency (CCE) reaches over 98 %, and specific energy consumption (SEC) is less than 715 kWh/t Bi. Compared with the traditional chloride system, the MSA-based membrane electrolysis medium has advantages of environmental friendliness, low occupational risks, low carbon and energy consumption, and can thus provide a sustainable green solution for bismuth hydrometallurgy.

A simple microcalorimetry system to determine the adsorption behaviour of acids in large adhesive bond gaps using base-initiated solution polymerisation of ethyl-2-cyanoacrylate

This work presents the use of a simple microcalorimetry cyanoacrylate (CA) polymerisation system for investigating aspects of CA adhesive cure through gap and adsorption of adhesive acid stabiliser by a range of metal and glass substrates. It is well established that strong acid induced inhibition periods (IPs) are almost directly proportional to the acid concentration in weak base initiated polymerisations of alkyl CAs in tetrahydrofuran (THF). Ethyl cyanoacrylate (ECA) polymerisation IP measurements were used to determine the adsorption of methanesulfonic acid (MSA) in THF or ECA solutions by a range of metal, glass and polypropylene (PP) lap shears surfaces. The extent of substrate acid sorption was found to decrease in the order: Copper-zinc alloy (C23000) > grit blasted mild steel > aluminium alloy 2024T3 > mild steel > glass > aluminium > stainless steel alloy 304 > PP. Differences in the extent of acid adsorption were accounted for in terms of two effects: surface acidity/basicity and surface area (roughness). The decrease in MSA concentration following lap shear immersion in an MSA solution was related to the reactivity of the substrates for catalysing bond line polymerisations as described in a recently reported confocal Raman spectroscopic study of ECA/substrate reactivity.

Synergistic inhibition effect of Mikania micrantha extract with potassium iodide on the corrosion of cold rolled steel in methanesulfonic acid solution

The synergistic inhibition effect of Mikania micrantha extract (MME) with KI mixture on the corrosion of cold rolled steel (CRS) in methanesulfonic acid (MSA) was conducted by weight loss, electrochemical techniques and surface characterizations. The experimental results indicate that either MME or KI performs moderate inhibition with a maximum inhibition efficiency below 74%. However, MME/KI mixture exhibits an efficient performance with a maximum inhibition efficiency of 91%. There is a synergism between MME and KI with a corresponding synergism parameter higher than 1. The alien invasive weed can be developed as a novel inhibitor against metallic corrosion.

Computer simulation study of ion-water and water-water hydrogen bonds in methanesulfonic acid solutions at room temperature

Classical molecular dynamics simulations of aqueous methanesulfonic acid solutions have been conducted at room temperature in the entire composition range. The dissociation of the acid has been considered according to the available experimental data. Then, the systems are constituted by the following molecular species: water and methanesulfonic acid molecules, hydronium cations, and mesylate anions. The simulations have been carried out employing a reliable force field, which provides density values that show an excellent agreement with the available experimental data. The shear viscosity, the diffusion coefficients of the molecular species, and the radial distribution functions, which involve water molecules, have also been computed. We have observed that water molecules diffuse faster than the other species at all concentrations. Moreover, the shear viscosity and the diffusion coefficients exhibit a noticeable unimodal concentration dependence with extrema located at 90 wt% (0.628 mol fraction). A detailed hydrogen bond analysis, concerning water molecules, has also been made. At low dilutions, water exhibits its well-known hydrogen bond tetrahedral structure, which vanishes as the acid concentration increases. The most labile water molecules are those bonded to the anions. At large concentrations, the lability of the water molecules, bonded to other water molecules, increases, and that of the water molecules, bonded to the cations, decreases. The interrupted lifetimes also show a unimodal dependence with maxima located at 90 wt%. This behavior could be related to the appearance of the methanesulfonic acid hydrogen bond network, which emerges at large weight percentage values because the acid almost completely dissociates up to concentrations of 70 wt% (0.304 mole fraction).

An efficient interface model to develop scalable methodology of melt processing of polypropylene with graphene oxide produced by an improved and eco‐friendly electrochemical exfoliation

AbstractThis study developed a scalable and straightforward adaptation methodology for melt processing of polypropylene (PP) to provide a high degree of exfoliation of multilayer graphene oxide (GO) by using a high‐shear mixer. GO was first produced by an improved and eco‐friendly electrochemical exfoliation by using an environmentally friendly aqueous methanesulfonic acid (MSA) and a sodium sulfate salt system to minimize the environmental impact. The produced GOs then were melt blended with PP and their mechanical, thermal, and morphological properties were investigated under different GO loadings to attain ideal configuration and increase interfacial interactions between polymer matrix and reinforcer. Comparisons were made by producing different PP composites using two different GO types produced in salt and acid environments. Additionally, by applying different voltages to salt system, the effect of applied voltage on the properties of both GO material and the composites were discussed. The characterization results indicated that GO obtained in MSA solution caused a 71% increase in flexural modulus and 46% in flexural strength with the addition of 1 wt% GO. The rheological characterization also showed that dispersion and viscosity improved with lower GO loadings compared to neat polymer by providing cost‐effective and scalable graphene manufacturing.

Electrocatalytic Oxidation of Ethanol on the Platinum Electrode in Solution of Methanesulfonic Acid

Electrocatalytic Oxidation of Ethanol on the Platinum Electrode in Solution of Methanesulfonic Acid

Mild Electrocatalytic Hydrodeoxygenation of Lignin-Based Phenolic Monomers in Polar Organic Electrolytes

In biomass upgrading process, complete oxygen removal is required to maximize the energy density of the final liquid product as fuel. Conventionally, this process is carried out at high pressure and temperature in the presence of externally supplied hydrogen gas. Electrocatalytic hydrogenation (ECH), which represents a novel approach for synthesis of renewable chemicals from biomass derivatives, is mostly performed in aqueous electrolytes under mild conditions (i.e., ambient pressure and low temperature), which are unfavorable for the deoxygenation.This work demonstrates that electrocatalytic hydrodeoxygenation (ECHDO) can be achieved at mild conditions (1 atm, 40–60 oC) using a stirred slurry catalyst in polar organic electrolytes. Lignin-based phenolic monomers (i.e., cerulignol, creosol, guaiacol, phenol) can be partially and fully deoxygenated to cyclic alcohols and cyclic alkanes, respectively, either individually (as a single reactant) or collectively (as a mixed reactant).Significant cerulignol conversion (~50%) was achieved in the polar organic electrolyte, consisting of methanesulfonic acid (MSA) solution (0.2 M) and 2-propanol (1:1 volume ratio), using slurry Pt/C catalyst after 4 h reaction (T = 50 oC, j = -182 mA cm-2, F.E. ≈ 60%). Propylcyclohexane was the most dominant product with good selectivity (~35%). In this dual catalytic system, Pt/C activates hydrogenation step while MSA solution provides acidity that favors dehydration and/or dehydroxylation steps. Meanwhile, the polar organic solvent (i.e., 2-propanol) improves reactant solubilization and affects proton stabilization, resulting in the higher reactivity of the acidic protons toward dehydration.In comparison to the other polar organic solvents being tested (e.g., ethanol, THF, dioxane, and acetone) in the ECHDO of cerulignol, the use of 2-propanol resulted in the highest reactivity (X = 71%, F.E. = 36%) under the identical reaction conditions. The experimental results clearly indicated that different polar organic solvents give different reactivities, possibly due to the different proton and substrate solvation effects. Overall, complete deoxygenation of phenolic compounds can be done via electrocatalysis at mild conditions and low Pt catalyst concentrations (0.6–2.8 wt.%) in the absence of external hydrogen gas.

Chemical Leaching of Sulfidic Mining Waste, Plombières Tailings Pond, Eastern Belgium: Insights from a Mineralogical Approach

Historic sulfidic mine waste material poses both an economic opportunity and an environmental threat (e.g., acid mine drainage). Due to low metal content in the mine waste and complex mineralogy, metal extraction of metal of interest is challenging. The Plombières tailings pond in eastern Belgium was selected as a case study to determine the potential for metal extraction of targeted metals from three different types of mine waste (metallurgical waste, brown, and yellow tailings). Material from this historic tailing originates from the exploitation and pyrometallurgical processing of the Mississippi Valley-type ores. The examined mine waste contains amounts of lead and zinc which can be potentially recovered by developing a hydrometallurgical method, which is selective for zinc and lead with respect to iron. From the three selected chemical extraction techniques, i.e., sulfuric acid, methanesulfonic acid, and sodium hydroxide solutions, the best results were given by sodium hydroxide solution leaching, due to negligible concentration of Fe in pregnant leaching solution, and leached metals were not precipitated into new mineral phases. Pb and Zn showed, however, a leaching efficiency of only 22% (0.0–63.6%) and 14% (0.0–29.1%) in average respectively. Furthermore, this study investigated how the mineralogy of mine waste material influences the leaching efficiency of the samples. Regardless of the lixiviant and the material, the highest leaching efficiency of Pb and Zn was achieved for samples where abundant Pb and Zn minerals were present. In samples where no Pb- or Zn-bearing minerals were detected, leaching efficiency was lower or negligible.

Electrochemical dissolution and recovery of tin from printed circuit board in methane–sulfonic acid solution

Current industrial Sn stripping processes from raw printed circuit board (PCB) are carried out typically in nitrate system and inevitably produce low-concentration NOX gas pollutant and high-concentration nitrate wastewater. This study proposes a novel and high-efficient Sn electrochemical stripping and recovery method from PCBs in methane–sulfonic acid (MSA) solution. A PCB covered with Sn was used as the anode, and Sn was removed by one-step method and deposited on the cathode in the electrolysis process. This work also investigated the influences of various electrolysis conditions on the change of current efficiency, electric power consumption, and PCB surface morphology. The optimal conditions were 40 °C, 60 g/L Sn2+, 100 g/L MSA, 60 mm inter-electrode spacing, and 200 A/m2 current density for Sn dissolution and extraction. About 85% of Sn was removed from the anodic PCB and subsequently electrodeposited at the cathode under the most suitable conditions. The electric power consumption was 63 kWh/t-Sn, and the electrolyte had a long lifetime. Moreover, the copper layer was not corroded, and no Sn remained on the surface of the anodic PCB after immersion in the picking solution. This novel technique provides an efficient alternative for Sn removal and recovery from PCB and will promote resource recycling and environment protection in raw PCB manufacturing industry.

Modification of cellulose in the solution of methanesulfonic acid

Modification of cellulose in the solution of methanesulfonic acid

Size-controlled electrodeposition of Cu nanoparticles on gas diffusion electrodes in methanesulfonic acid solution

In this paper electrodeposition is used to obtain Cu nanoparticles, as it allows good control over particle size and distribution. These Cu particles were deposited onto a gas diffusion electrode which increased the resulting surface area. Prior to deposition, the surface was pre-treated with NaOH, HNO3, MQ and TX100 to investigate the influence on the electrodeposition of Cu on the gas diffusion electrode (GDE). When using HNO3, the smallest particles with the most homogeneous distribution and high particle roughness were obtained. Once the optimal substrate was determined, we further demonstrated that by altering the electrodeposition parameters, the particle size and density could be tuned. On the one hand, increasing the nucleation potential led to a higher particle density resulting in smaller particles because of an increased competition between particles. Finally, the Cu particle size increased when applying a greater growth charge and growth potential. This fundamental study thus opens up a path towards the synthesis of supported Cu materials with increased surface areas, which is interesting from a catalytic point of view. Larger surface areas are generally correlated with a better catalyst performance and thus higher product yields. This research can contributed in obtaining new insides into the deposition of metallic nanoparticles on rough surfaces.

A near-infrared azadipyrromethene dye: Photophysical properties under different acidity conditions

We designed and synthesized the new structure azadipyrromethene from 4-bromo-2-hydroxyacetophenone through five steps, and tested the compound via five different acid conditions. The results indicated that the maximum ultraviolet absorption wavelength of azadipyrromethene is 763 nm, and the addition of methanesulfonic acid and hydrochloric acid solution significantly increased the ultraviolet absorbance of the compound within 10 h, but the fluorescence quantum yield decreased from 0.71 to around 0.05. However, under the condition of phosphoric acid, the photophysical properties of azadipyrromethene did not change significantly.

The di(thiourea)gold(I) complex [Au{S=C(NH2)2}2][SO3Me] as a precursor for the convenient preparation of gold nanoparticles

Abstract The synthesis of [Au{S=C(NH2)2}2][SO3Me] (1) (a) by the anodic oxidation of gold metal in an anolyte of thiourea and methansulfonic acid and (b) by the reaction of Au(OH)3 with an aqueous solution of methanesulfonic acid in the presence of thiourea is reported. The structure of 1 in the solid state has been determined by single-crystal X-ray diffraction showing a linear S–Au–S unit with the thiourea ligands in a leaflet structure folded by 113.2(3)°. The cation of complex 1 is a dimer, based on short S · · · C interactions between two adjacent mononuclear cations. The thermal decomposition behavior of 1 was studied by TG and TG-MS confirming that it decomposes under inert gas or oxygen atmosphere in four steps in the temperature range of 200–650°C. Initial decomposition starts with the release and fragmentation of one of the thiourea ligands, followed by the anion degradation. Powder X-ray diffraction studies specified the formation of gold metal. Based on this observation, complex 1 was used as precursor for the formation of gold nanoparticles (Au NPs) in 1-hexadecylamine (c = 4.0 mol L−1) at T = 330°C without any addition of reducing agents. TEM, electron diffraction, and UV/Vis spectroscopy studies were carried out. Au NPs of size 15 ± 4 nm were formed, showing the characteristic surface plasmon resonance at 528 nm.

Gold(I) carboxylates and [Au(C(NH2)2(=S))2][SO3Me] for the deposition of gold and gold-doped SiOX materials by the atmospheric pressure combustion CVD process

Complexes [AuO2CCH2OMe(PR3)] (3a, R = Et; 3b, R = nBu) were prepared by the reaction of [AuCl(PR3)] (1a, R = Et; 1b, R = nBu) with [AgO2CCH2OMe] (2), while [Au(C(NH2)2(=S))2][SO3Me] (4) was synthesized by electrolysis of Au in presence of thiourea in an aqueous solution of methanesulfonic acid. The thermal behavior of 3a,b and 4 was investigated by thermogravimetry (TG), displaying that 3a,b decompose in a single step, which contrasts the three-step decomposition of 4. TG-MS coupled experiments (MS = mass-spectrometry) were performed with 3b, proving that at first decarboxylation occurs, which is evidenced by the detection of CO2+. Complexes 3a,b and 4 were applied as CCVD (combustion chemical vapor deposition) precursors for the formation of gold deposits and gold-doped SiOx materials in presence of hexamethyldisiloxane (HMDSO) on silicon and glass substrates. In the combined depositions of gold and SiOx, 3a,b gave a granulated surface morphology, whereby samples deposited from 4 and HMDSO showed a porous structure as evidenced by SEM (scanning electron microscopy). The gold deposits exhibit separated particles at the substrate surface, whereof the sample deposited from 4 showed the highest amount of gold (3a,b, 3.8 at-% Au; 4, 13.3 at-% Au) as proven by XPS (X-ray photoelectron spectroscopy). The Au content of the appropriate SiOx:Au materials amounts to 1.2 at-%. XPS detail spectra of the Au 4f peaks confirm the predominant formation of Au(0) next to Au2O3. XPS depth profile measurements of the SiOx:Au samples confirmed a higher gold content when precursor 4 was applied instead of 3a,b. The as-deposited samples were used in heterogeneous catalysis for the reduction of 4-nitrophenol to 4-aminophenol with NaBH4, whereby the ones deposited from 4 (with and without a SiOx matrix) show the highest catalytic activity.

Sampling and analysis of airborne ammonia in workplaces of China.

ObjectivesWith the increasing demand for the detection of occupational hazard factors in workplaces, the national standard determination method for ammonia (sampling with absorbing solution‐analysis with Nessler reagent spectrophotometry) in the air of workplace presents many drawbacks during application in China. This review summarized the improvement and the alternate methods of the current sampling and analysis procedures for ammonia, aiming to provide reference to establish an appropriate method for the determination of ammonia in workplace air.MethodsScientific publications in English and Chinese and the standard methods of the Deutsche Forschungsgemeinschaft (DFG) in Germany, the National Institute for Occupational Safety and Health (NIOSH) and Occupational Safety and Health Administration (OSHA) in the United States, and Ministry of Health in China for airborne ammonia collection and analysis in the workplace were reviewed.ResultsThe measures to improve the current sampling and analysis procedures for ammonia in China were firstly summarized. For sampling, the decrease of absorbing solution concentration and the methanesulfonic acid solution as the alternate sampling solution were suggested. For analysis, the anti‐interference measures and the optimum reaction condition between ammonia and Nessler reagent were discussed. The alternate methods including sampling conducted using solid sorbent tubes and analysis performed by ion chromatography were then considered for the determination of ammonia.ConclusionsThe methods—sampling with acid‐treated solid sorbent tubes and analysis with ion chromatography—were more suitable for the determination of ammonia in workplace air. However, some details about ammonia sampling and analysis still need further investigation.

Highly Efficient AuPd Catalyst for Synthesizing Polybenzoxazole with Controlled Polymerization

Summary Using nanoparticles (NPs) to catalyze chemical reactions for the formation of functional polymers with controlled polymerization is an important field of chemical research. In this article, we report an AuPd NP system as an active and stable catalyst to catalyze one-pot reaction of formic acid, 1,5-diisopropoxy-2,4-dinitrobenzene, and terephthaldehyde, leading to the controlled polymerization and the formation of polybenzoxazole (PBO) (Mw = 3.6 kDa). The one-pot reaction is AuPd NP size and composition dependent, and 8-nm Au39Pd61 NPs are the best catalyst for the polymerization. The highly pure PBO shows excellent thermal stability up to 600°C and improved chemical and mechanical stability under challenging environmental conditions compared with commercial PBO (Zylon, Mw = 40 kDa). The reported NP-catalyzed one-pot reaction to polymerization is not limited to the formation of PBO but can be extended as a general approach to rigid polymers that are important for ballistic fiber, anti-flame, and smart-textile applications.

Restoring the Reactivity of Organic Acid Solution Used for Silver Recovery from Solar Cells by Fractional Distillation

Methanesulfonic acid (MSA) is used to recover silver (Ag) from solar cells by adding an oxidizing agent. It is possible to regenerate by substituting of H+ for Ag+, and thus it can be reused for additional reactions. However, MSA is highly hygroscopic, and as an oxidizing agent can easily decompose in the acidic environment during Ag extraction, leading to dilution due to the formation of H2O. This H2O in the MSA solution hinders the Ag extraction. In this study, we present a fractional distillation process for restoring the reactivity of reused MSA solutions by reducing the H2O content. Our results showed that the reactivity of the separated MSA was restored and Ag could be recovered from the solar cell.

Kinetics and mineralogical analysis of copper dissolution from a bornite/chalcopyrite composite sample in ferric-chloride and methanesulfonic-acid solutions

Ore samples contain a variety of copper-bearing and gangue minerals that affect the leach kinetics. The kinetic behaviour of a natural ore sample (that contained 48.7% bornite and 15.8% chalcopyrite) in a solution of methanesulfonic acid and ferric chloride was studied. The dependence of the reaction kinetics on the acid and oxidant concentration, temperature and particle size was investigated. The reaction activation energy was calculated using two methods, by empirical kinetic equations and by the ‘time-to-a-given-fraction’ method. The shrinking-core-model was fitted according to diffusion through a product layer, and an average apparent activation energy of 79.3 kJ mol−1 was obtained. Three apparent activation energies were obtained by the ‘time-to-a-given-fraction’ method; that for a copper extraction below 20% was 15.6 kJ mol−1 for copper intermediate formation, that between 20% and 50% copper extraction was 42.3 kJ mol−1 associated with sulfur formation and that for dissolution above 50% was 76.5 kJ mol−1 for the final stage when the sulfur layer is covering the entire particle surface. The presence of chalcopyrite in the sample increased the average activation energy by 69% compared with a pure bornite sample. The leach products had different textures; the sulfur formed from chalcopyrite showed a more porous texture than that formed from bornite. These differences in texture are expected to affect the lixiviant access.